Table 3. ROBINS-I tool for the evaluation of bias.

ROBINS-I: Risk of Bias In Non-randomized Studies of Interventions.

Author	Confounding	Selection of participants	Classification of interventions	Deviation from intended interventions	Missing data	Measuring outcomes	Selection of the reported result	Overall
Andersson et al. [19]	Moderate	Moderate	Low	Low	Low	Moderate	Low	Moderate
Bragg et al. [32]	Low	Low	Low	Low	Low	Low	Low	Low
Brown et al. [20]	Low	Low	Low	Low	Low	Low	Low	Low
Cohen et al. [21]	Serious	Moderate	Low	Low	Low	Serious	Low	Serious
Guo et al. [38]	Low	Moderate	Low	Low	Low	Low	Low	Moderate
Fung et al. [22]	Moderate	Moderate	Low	Low	Low	Moderate	Low	Moderate
Hatch et al. [23]	Moderate	Moderate	Low	Moderate	Moderate	Moderate	Low	Moderate
Hu et al. [24]	Moderate	Moderate	Low	Low	Low	Moderate	Low	Moderate
Leung et al. [33]	Serious	Moderate	Low	Low	Low	Serious	Low	Serious
Ma et al. [25]	Low	Moderate	Low	Low	Low	Low	Low	Moderate
Maserejian et al. [26]	Low	Moderate	Low	Low	Low	Low	Low	Moderate
Mirghani et al. [34]	Moderate	Moderate	Low	Low	Low	Moderate	Low	Moderate
Park et al. [27]	Low	Moderate	Low	Low	Low	Low	Low	Moderate
Rebholz et al. [28]	Low	Moderate	Low	Low	Low	Low	Low	Moderate
Sakaki et al. [29]	Low	Moderate	Low	Low	Low	Low	Low	Moderate
Samman et al. [35]	Low	Moderate	Low	Low	Low	Low	Low	Moderate
Schernhammer et al. [30]	Serious	Moderate	Low	Low	Low	Serious	Low	Serious
Stamates et al. [39]	Low	Moderate	Low	Low	Low	Low	Low	Moderate
Sumorok et al. [37]	Low	Moderate	Low	Low	Low	Low	Low	Moderate
Vyas et al. [31]	Low	Moderate	Low	Low	Low	Low	Low	Moderate
Yu et al. [36]	Low	Low	Low	Low	Low	Low	Low	Low